At the moment, I'm usually walking between Waterloo and Logica Stephenson House.
That's about a 40 minute walk each way.
I think of this as very cheap exercise, because it would take about 25 minutes on the tube, so I am getting 40 minutes exercise each way for only 15 minutes "spent".
Whereas if I (for example) went swimming or playing squash, or running on a treadmill at the gym, it would be more like 40 minutes of exercise for 100 minutes spent (when you add on travelling to and from the gym, changing, showering, and so on).
On a related topic, I guesstimate that at the moment, running accounts for around 15% of my total calorie expenditure. That's significant. If I walk to and from Waterloo three days a week, that would be about 7%. Of course, there's also walking to and from Winchester and New Malden stations....
I don't really know how many calories per hour weight training burns. It's much harder to quantify how "hard" you're doing it (whereas with running, mins/mile provides an easy measurement).
